Stand alone fuel injection system

Abstract

An electronic fuel injection system operable as a bolt on retro fit replacement for a wide variety of carburetors is disclosed. The system includes a throttle body-injector assembly which, by means of an adapter may be bolted directly to stock intake manifolds using the carburetor mounting bolt holes in the manifold. The throttle body passages and injectors are designed to meet the fuel and air delivery requirements of large displacement engines and an electronic control unit which controls the solenoid actuated injectors in a duty cycle operation is provided with externally accessible adjustments by means of which the system may be adjusted to tune the rate of fuel injection to the fuel delivery requirements of engines of displacements much smaller than the largest displacement engine within the systems capability. The system may be independently adjusted for optimum or user selected economy or power operation at idle, mid range and high rpm engine operation and further includes choke and accelerating enrichment adjustments. The control unit also controls operation of the fuel pump to maintain a constant injection pressure at all times.

I claim: 
     
       1. A stand-alone throttle body fuel injection system including fuel injector means for injecting fuel from a throttle body into the fuel-air inlet of an engine manifold, comprising: an electronic control means for controlling the activation of the fuel injector, the electronic control means comprising:   means for generating a pulse width modulated signal having a predetermined frequency and pulse width to the fuel injectors;   frequency signal generating means, responsive to the engine RPM, for generating a signal to the pulse width modulated signal generating means having a frequency proportional to the engine RPM;   pulse width signal generating means, responsive to the engine throttle position, for generating a signal to the pulse width modulated signal generating means having a pulse width proportional to the engine throttle position;   throttle position sensor means for sensing the throttle position and generating an output proportional thereto;   means, responsive to the engine RPM, for generating an engine RPM signal; and   an accelerator pump adjustment means adjustably responsive to a full open position of the throttle plate sensor means, the accelerator pump adjustment means input to the pulse width signal generating means and the frequency signal generating means to increase the pulse width and the frequency in proportion thereto.   
     
     
       2. A fuel injection system for an internal combustion engine having a fuel supply tank and an intake manifold having a fuel-air mixture inlet; said system comprising a throttle body having a combustion air passage means extending therethrough from a combustion air inlet to an outlet, adjustably positionable throttle means in said combustion air passage means for controlling the flow of a fuel-air mixture therethrough, adaptor means for mounting said throttle body on said manifold with the outlet of said combustion air passage means opening into said fuel-air mixture inlet of said manifold, cyclically operable fuel injection means on said body for cyclically injecting pulses of fuel into said combustion air passage means, fuel pump means for pumping fuel to said injection means from said fuel supply tank, control means including throttle position sensing means and engine speed sensing means for cyclically actuating said injection means to inject fuel into said passage in pulses of time durations and cyclic frequencies variable in response to variations in throttle position and engine speed respectively sensed by said throttle position and said engine speed sensing means, and manually operable adjustment means on said control means for establishing independently selected fuel to air mixture ratios during idle, mid range, and high speed operations of said engine.   
     
     
       3. A stand-alone throttle body fuel injection system including fuel injector means for injecting fuel from a throttle body into the fuel-air inlet of an engine manifold, comprising: an electronic control means for controlling the activation of he fuel injector, the electronic control means comprising:   means for generating a pulse width modulated signal having a predetermined frequency and pulse width to the fuel injectors;   frequency signal generating means, responsive to the engine RPM, for generating a signal to the pulse width modulated signal generating means having a frequency proportional to the engine RPM;   pulse width signal generating means, responsive to the engine throttle position, for generating a signal to the pulse width modulated signal generating means having a pulse width proportional to the engine throttle position;   throttle position sensor means for sensing the throttle position and generating an output proportional thereto;   means, responsive to the engine RPM, for generating an engine RPM signal;   first idle adjustment means, input to the pulse width signal generating means, for establishing a base idle pulse width;   second mid-range adjustment means, responsive to the throttle position sensor means, for varying the pulse width when the throttle position is at a position corresponding to mid range engine RPM operating conditions; and   third adjustment means, input to the pulse width signal generating means, for adjusting the pulse width under high RPM engine operating conditions.   
     
     
       4. The fuel injection system defined in claim 3 wherein said fuel injection means comprises a plate like adapter member adapted to be fixedly and sealingly mounted on said manifold in overlying relationship with said fuel-air mixture inlet and having means for fixedly and sealingly mounting said throttle body on said plate like adapter member in overlying relationship to said adapter member, said adapter member having first passage means therethrough for establishing direct fluid communication between the combustion air passages means in said throttle body and said fuel-air mixture inlet of said manifold, and second passage means through said adapter member for circulating engine coolant through said member. 
     
     
       5. The fuel injection system defined in claim 4 wherein the adpater member is disposed in the engine compartment of a vehicle and the control means is mounted in the vehicle separate and isolated from the engine compartment. 
     
     
       6. A fuel injection system for an internal combustion enging having a fuel supply tank and an intake manifold having a fuel-air mixture inlet; said system comprising a throttle body having a combustion air passages means extending therethrough from a combustion air inlet to an outlet, adjustable positionable throttle means in said combustion air passage means for controlling the flow of a fuel-air mixture therethrough, adaptor means for mounting said throttle body on said manifold with the outlet of said combustion air passage means opening into said fuel-air mixture inlet of said manifold, said adapter means comprising a plate like member adapted to be fixedly and sealingly mounted on said manifold in overlying relationship with said fuel-air mixture inlet and having means for fixedly and sealingly mounting said throttle body on said plate like member in overlying relationship to said member, said member having first passage , means therethrough for establishing direct fluid communication between said combustion air passage means in said throttle body said fuel-air mixture inlet of said manifold, and second passage means through said member for circulating engine coolant through said member, cyclically operable fuel injection means on said body for cyclically injecting pulses of fuel into said combustion air passage means, fuel pump means for pumping fuel to said injection means from said fuel supply tank, control means including throttle position sensing means and engine speed sensing means for cyclically actuating said injection means to inject fuel into said passage in pulses of time durations and cyclic frequencies variable in response to variations in throttle position and engine speed respectively sensed by said throttle position and said engine speed sensing means, and adjustment means on said control means for establishing independently selected fuel to air mixture ratios during idle, mid range, and high speed operations of said engine.   
     
     
       7. The fuel injection system defined in claim 6 wherein said combustion air passage means comprises a pair of combustion air passages extending vertically therethrough, said injector means including a pair of fuel injectors each having a fuel inlet and a fuel discharge nozzle assembly with the nozzles of the injectors fixedly mounted upon said body in aligned overlying relationship to the respective combustion air passages, pressure regulator means fixedly mounted on said body and having a fuel chamber therein in constant fluid communication with said fuel pump means and with said injector fuel inlets, and means for maintaining the pressure of fuel within said chamber at a selected constant pressure. 
     
     
       8. The fuel injection system defined in claim 7 wherein said control means includes means for regulating said fuel pump means to cause said pump means to pump fuel to said fuel chamber at a rate greater than the rate at which fuel is injected into said combustion air passages by said injector means, and presssure responsive valve means in said pressure regulating means for discharging excess fuel from said chamber to said fuel tank to maintain said selected constant pressure within said chamber. 
     
     
       9. The fuel injection system defined claim 7 wherein said injector assemblies each include a solenoid actuated valve controlling fluid communication between said fuel inlet and said fuel discharge nozzle, and said control means comprises means for supplying a first pulse width modulated signal to cyclically energize and deenergize the valve solenoid to discharge fuel from said nozzle in pulses of a frequency and time duration controlled by said throttle position sensing means and said engine speed sensing means and for supplying a second electrical signal operable to cause said fuel pump means to maintain said selected constant pressure at the fuel inlet of the injector. 
     
     
       10. A stand-alone throttle body fuel injection system including fuel injector means for injecting fuel from a throttle body into the fuel-air inlet of an engine manifold, comprising: an electronic control means for controlling the activation of the fuel injector, the electronic control means comprising:   means for generating a pulse width modulated signal having a predetermined frequency and pulse width to the fuel injectors;   frequency signal generating means, responsive to the engine RPM, for generating a signal to the pulse width modulated signal generating means having a frequency proportional to the engine RPM;   pulse width signal generating means, responsive to the engine throttle position, for generating a signal to the pulse width modulated signal generating means having a pulse width proportional to the engine throttle position;   throttle position sensor means for sensing the throttle position and generating an output proportional thereto;   means, responsive to the engine RPM, for generating an engine RPM signal, and   manually operable adjustment means on said control means and input to the pulse width modulated signal generating means for establishing independently selected fuel to air mixture ratios during idle, mid range and high engine RPM operations, the adjustment means being at least responsive to the throttle position sensor means when the throttle position is at a position corresponding to mid range engine RPM operating conditions.   
     
     
       11. The system of claim 10 further including: first idle adjustment means, input to the pulse width signal generating means, for establishing a base idle pulse width.   
     
     
       12. The system of claim 10 wherein the frequency signal generating means comprises: a voltage controlled oscillator.   
     
     
       13. The fuel injection system defined in claim 10 wherein said fuel injection means comprises a plate like adapter member adapted to be fixedly and sealingly mounted on said manifold in overlying relationship with said fuel-air mixture inlet and having means for fixedly and sealingly mounting said throttle body on said plate like adapter member in overlying relationship to said adapter member, said adapter member having first passage means therethrough for establishing direct fluid communication between the combustion air passage means in said throttle body and said fuel-air mixture inlet of said manifold, and second passage means through said adapter member for circulating engine coolant through said member. 
     
     
       14. The system of claim 10 further including: throttle position sensor means for sensing the throttle position and generating an output proportional thereto; and   means, responsive to the engine RPM, for generating an engine RPM signal.   
     
     
       15. The system of claim 14 further including: second mid-range adjustment means, responsive to the throttle position sensor means, for varying the pulse width when the throttle position is at a position corresponding to mide range engine operating conditions.   
     
     
       16. The system of claim 14 further including: third adjustment means, input to the pulse width signal generating means, for adjusting the pulse width under high engine operating conditions.   
     
     
       17. The system of claim 14 further including: means, responsive to the ignition switch of the engine, the throttle position sensor means, and the engine RPM, for varying the speed of the fuel pump of the engine in proportion to the engine RPM.   
     
     
       18. The system of claim 14 further including: fast idle solenoid driver means for driving a fast idle solenoid;   engine coolant temperature sensor means for sensing the coolant temperature of the engine; and   temperature adjustment means for adjusting the pulse